Paediatrics (RCH) - Theses
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ItemMinimising complications after surgical repair of coarctation of the aorta( 2018)Coarctation of the aorta is one of the most common congenital heart defects, often requiring surgery soon after birth. In Australia alone, approximately 150 babies are born with coarctation each year with an estimated 3,000 people living with a coarctation repair. Coarctation can no longer be considered a benign condition cured by surgery. There has been renewed interest into the late outcomes after coarctation repair as rates of late aortic arch reobstruction and late hypertension have recently been demonstrated to be much higher than initially expected. Alarmingly, studies have demonstrated that this late hypertension is directly linked to mortality at a young age. Unfortunately, late hypertension is often resistant to conventional antihypertensive medication and its exact mechanism is unknown. This thesis aimed to (i) determine the long-term outcomes after surgical repair of coarctation with a particular focus on determining the mechanisms leading to the development of late hypertension, (ii) examine the impact of an associated bicuspid aortic valve on patients with previous coarctation repair, and (iii) examine the complication of vocal cord paresis after aortic arch repair via sternotomy approach. A broad range of potential mechanisms for late hypertension including mechanical, arterial wall, neural, and genetic factors were all explored. In this thesis, I present our current understanding of the population, their outcomes and risk factors for early and late complications, and, finally, present initial data serving as a foundation for a prospective aortic arch anomaly biobank and hypothesis-generated research. Through a collaboration with the Royal Brompton Hospital, London, UK, this thesis has also resulted in the largest and longest cohort study in the world comprising 834 coarctation patients spanning seven decades of follow-up. Through this thesis, I have demonstrated that: (i) there is likely a high prevalence of late hypertension after coarctation repair, (ii) there is significant device-dependence of 24-hour blood pressure monitoring devices, making the identification of the hypertensive patient challenging, (iii) the risk of late mortality is three times higher than a healthy matched population, with the majority of deaths attributable to complications related to hypertension, (iv) there is four times increased risk of aortic valve and ascending aortic interventions in those with an associated bicuspid aortic valve, (v) the use of extensive aortic arch repair techniques may reduce long-term complications, and (vi) there is a high incidence of left vocal cord paresis after aortic arch repair via sternotomy approach. This journey began when I was an undergraduate medical student investigating the outcomes of patients with coarctation repaired at The Royal Children’s Hospital. This thesis has refined our understanding and management of complications after coarctation repair and will ultimately improve the long-term outcomes of many patients with coarctation of the aorta.